Well, there are a couple of reasons I think this is different:

1. APs are static and not mobile, versus Bluetooth devices – which can move, and are more importantly personally associated with a person. That inherently provides opportunities for more leakage on information, since device addresses can now be used to track people.

2. Devices aren't just advertising their existence. They're also advertising their services, and in some cases actually just sending whatever data a client asks for. There's a particular brand of iPad stylus which seems to just open up and send it's accelerometer readings to any device which connects. There seem to be heart-rate monitors that do the same.

For me, it's much more worrying that devices happily broadcast personal information without authentication – I don't actually think device advertisement is a big deal in comparison!

I suspect the GP is just referring to the stuff they happen to be transmitting in the clear right now because they weren't thinking about the risks. Basically like early days 802.11 when you needed to pay big money for something like wireshark.

You could track people around a fairly good area, like a shopping mall, using off-the-shelf, inexpensive Bluetooth hardware and just keeping track of where various IDs turn up. Indoors, that's probably much more accurate tracking than you could perform using cellular triangulation. It's more like the kind of tracking you do using RFID tokens in a warehouse.

I don't know if it's a problem per se, but it's something people should be aware of; many devices are constantly broadcasting a unique identifier almost all the time unless they take steps to turn it off.

I can't tell whether you're referring to Bluetooth, WiFi, or both. WiFi is worse (longer range) and I suspect more widely used and likely to be left on on phones.